Case and point: zinc. A healthy man only needs about 11mg (8 for women) of the stuff per day, but if you become deficient in it, there are some unpleasant consequences. According to the National Institutes of Health, zinc deficiency is characterized by loss of appetite and impaired immune function. In some extreme cases of zinc deficiency, people have experienced weight loss, lethargy, hair loss, and diarrhea.

“Zinc performs many crucial functions in the body, such as supporting a healthy immune system and helping proper wound healing,” says Erin Stokes, a naturopathic doctor. “Zinc is also important for our eyesight, as well as our senses of taste and smell.”

It’s vital for gym rats

If you’re working out most days of the week, either in the gym or on the running track, your need for zinc might be greater than the average person’s.

“Zinc plays a role in tissue repair, as well as testosterone production,” Stokes says. In other words, if you’re deficient in the micronutrient, all your work in the gym could be for naught.

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Your diet might not include it

If you’re an omnivore, your chances of being zinc deficient are low. Oysters are close to five times your recommended daily intake, and beef has almost half. Vegans and vegetarians, though, have fewer options.

An ounce of pumpkin seeds only has 2.2 mg of zinc, about 15 percent of your recommended daily dose. So you’d have to eat more food to get to the levels needed, or take a supplement.

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Do you need to supplement?

Everyone should consider supplementing with zinc, but men have reason to be more concerned about their levels than women.

“Zinc is important for both men and women, but since it is used in the production of testosterone, it has particular importance for men,” Stokes says.

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How much?

Stokes recommends 15-25 mg of zinc amino acid chelate per day. You can take more if you’re immune system is stressed, Stokes says, but don’t go above 40 mg per day.

“You do not want to supplement above this amount unless it’s only for a very short period of time, since excess zinc can lower levels of copper.”

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What to look for

Stokes recommends looking for a supplement that contains zinc amino acid chelate, which the body can more easily absorb than zinc sulphate, according to studies. It also doesn’t need to be a dedicated zinc pill.

“For many people a high quality multivitamin provides the zinc needed to supplement gaps in the diet,” Stokes says.